1. Field of the Invention
The present invention relates to a cam grinding machine for grinding a cam shaft and, more particularly, to a swing table support device in the cam grinding machine.
2. Description of the Prior Art
Recently, in order to improve grinding efficiency of cam grinding machines, the grinding wheel is rotated at a higher speed or a grinding wheel made of cubic boron nitride (CBN) is used which can be fed toward a workpiece to be ground at a higher feed rate. A conventional swing table and a support thereof in a cam grinding machine for a cam shaft cannot meet these requirements due to a lack of rigidity. In the conventional cam grinding machine, the swing table is swingably supported on the traverse table at its opposite ends and at the middle portion thereof. The intermediate support is mounted on the traverse table at the same surface as that mounting the opposite supports and therefore the flange portion thereof projects beyond the upper mounting surface of the traverse table. Accordingly, in order to prevent interference of the swing table with the flange portion of the intermediate support at its swing ends, a considerable portion of the lower side walls of the swing table has to be eliminated or cut away. This results in lowering the rigidity of the swing table.
Furthermore, in order to swingably support the swing table by the intermediate support, a shaft is fixed in the intermediate support and the opposite ends of the shaft are inserted through bearings in a pair of inside walls depending from the underside of the swing table. A cantilever boring tool has to be moved from one side of the swing table in order to make bores on the inside walls for bearing support, which results in dispersion of the finished bores. This is another factor of lack of rigidity of the swing table.